


you're the sweetest thing underneath the sun

by drfitzmonster



Series: Mommates AU [2]
Category: Supergirl (TV 2015)
Genre: Accidental Coparenting, Alternate Universe - Human, Domestic Fluff, F/F, First Kiss, Found Family, Kid Fic, Love Confessions, Roommates, Sharing a Bed, Storytelling
Language: English
Status: Completed
Published: 2019-12-03
Updated: 2019-12-03
Packaged: 2021-02-26 18:27:51
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,358
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21653038
Author URL: https://archiveofourown.org/users/drfitzmonster/pseuds/drfitzmonster
Summary: Kara spends the morning with a four year old who thinks she’s a shark and the woman who she’s desperately in love with.
Relationships: Kara Danvers/Lena Luthor
Series: Mommates AU [2]
Series URL: https://archiveofourown.org/series/1560904
Comments: 72
Kudos: 808





	you're the sweetest thing underneath the sun

**Author's Note:**

> This is an AU of an AU. It started out as a ficlet, and like most of the other ficlets I’ve written for Mommates AU, **it is not in continuity and does not fit the timeline of the main fic** ([for once in my life](https://archiveofourown.org/works/11514405)).
> 
> It works (I think) even if you haven't read the first fic in the series. I really hope you enjoy all the cute stuff.

Kara woke to a small hand smacking her gently, and when she opened her eyes she was looking a plastic shark dead in the face. She gasped and sat straight up. “Oh no! There’s a shark in my bed!”

“Momma! I want up!” Libby demanded, making grabby hands.

Kara lifted her onto the bed. “Did you put a shark in my bed you silly goose?”

“I’m not a goose I’m a shark!”

“Oh, of course. Thank you for correcting me. But let’s try to be quiet, ok? Mommy is still sleeping.”

Libby nodded seriously, looking over at where Lena was curled into Kara’s side. “Ok, Momma.” She picked up her toy, wagging her finger at it. “Shhhh... Momma says be quiet.” She tucked the shark under her arm and clambered into Kara’s lap.

“Tell me the Momma story.”

“Again?”

“Yes! Again!”

“Shhh, sweetie, we’re being quiet so Mommy can sleep, remember?”

“Oh, right,” she whispered. “Momma please tell the story.”

“Ok, ok.” Kara laughed, taking Libby’s hand in hers, like she always did when she told this story. “When you were a little, tiny baby, just five months old...” She picked up Libby’s hand and asked, “Can you count to five with me?” using Libby’s fingers to count one, two, three, four, five. “That’s right! You’re getting so good at counting, baby. I’m so proud of you!”

“When you were five months old, you and your Mommy came to stay with me. You were so tiny.”

“How tiny was I, Momma?”

“You were really tiny. I could barely even see you. I had to use a magnifying glass.”

Libby laughed and grabbed Kara’s hand. “Nuh uh, Momma,” she insisted, in a voice that was as close to a whisper as Kara could hope for. “You’re fibbing.”

“I am not. Ask your Mommy.”

“I can’t. She’s asleep.”

“Well, I guess you’ll just have to believe me then. You were itty itty itty bitty, like a little tiny microscopic baby.”

“Nuh uh! Mommy showed me pictures.”

“Ok, fine. You’re too smart for me. You weren’t _that_ little, but you were pretty tiny. And you hardly had any hair.”

“I was bald!”

“You were. You had to wear hats to protect your sweet little head.” Kara bent to press a kiss into Libby’s hair. “I love you so much, Libby.”

“I love you too, Momma. What happens next?”

“Then you met your best friend.”

“Krypto!”

“That’s right, baby, but maybe we should go to the living room for the rest of this story so we don’t wake up Mommy.”

“No, you’re just getting to my favorite part,” Lena said into a yawn, her voice raspy from sleep.

“Mommy’s awake!”

Lena sat up with a groan. “I am, darling.”

She sprang out of Kara’s lap and into Lena’s, kicking Kara right in the gut as she did so.

“Oof, Libby, be careful with your feet. You got me in the tummy.”

Libby flopped onto her back, draped between the two of them, her head in Lena’s lap, feet on Kara’s leg.

“Sorry, Momma. I just got ‘cited to see Mommy.”

“I know you did, baby. I accept your apology. Do you want me to keep telling the story?”

“I want Mommy to tell the rest!”

Lena smiled and brushed her fingers through Libby’s hair. “Krypto fell in love with you the first time he ever met you, and since then he’s followed you everywhere you go.”

“Am I his favorite?”

“Yes, baby. Even more than Momma.”

“Krypto loves me the most!”

“He does,” Kara said, pulling a sour face and a pout, which spurred Libby to try and comfort her.

“Momma it’s ok,” she said, wriggling into a position where she could grab Kara’s face in her hands. “He loves you, jus’ not as much as me. Ok?”

“I guess...” Kara said, feigning resignation as Libby gently patted her cheek.

“More story, please, Mommy,” she said, settling back into Lena’s lap.

“I can’t remember what comes next.”

Libby glared up at Lena, unimpressed with her recall. “ _Mommy_. It’s when I _talked_. How can you forget?”

“I’m sorry, baby. You know Mommy is not quite as good at telling this story as Momma is.”

“No, Mommy, you say it good too.”

“Thank you, sweetheart.” She cleared her throat, ready to continue the story. “Your very first word was _mama_. Do you remember who you said it to first?”

“Momma!”

“That’s right! And who else did you call mama?”

“You! I had two mommas!”

“But you don’t have two mommas now?”

“No because you turned to a mommy. Now I have a momma _and_ a mommy!”

Libby had claimed Kara as her mother with her very first word, regardless of how Kara or Lena felt about the implications. It was dangerous territory, but neither of them was willing to deny Libby what she very clearly needed.

So Kara was Momma, and that was that. She and Lena never really talked about it. It was another murky, amorphous truth, like the fact that both of them slept better in each other’s arms than they ever had apart, that just existed as it was, defying exact definition and lurking at the edges of what they could bring themselves to say out loud.

What was there to say anyway? How could Kara even begin to describe the depth of what she felt for Lena and her daughter? It was the rawest, most vulnerable kind of love, the fiercest, most precarious.

She didn’t know what to say to Lena, how to tell her the _real_ truth, the root, the elemental truth, the axiom upon which Kara’s entire world had been rebuilt the moment Lena and Libby entered her life.

Which was that she loved them, fully, with her whole heart, that they had become her world, her sky and her entire cosmos. There was nothing else but them.

That was the difficult truth, artless and clumsy but unwavering.

She didn’t know what to do with it, so she took it and hid it somewhere safe: among all the smaller, more mundane truths, calling it the Momma story. It was concrete and simple, just the facts ma’am, but embellished for dramatic effect (there was a child with an irrepressible imagination involved, after all).

Every time Kara told the story, it was a little different. There were always many interjections from Libby. Kara changed up the teasing every time because it made Libby giggle so much. Sometimes she talked about how tiny she was, or how loud she cried, or how she pooped so much the store ran out of diapers. Every time Libby would squeal with delight and tell Kara she was fibbing, and Kara would deny it a couple of times before laughing and conceding to Libby’s superior intelligence.

It was not the kind of story they ever finished, and the ending was different every time, depending on how quickly Libby got bored and wanted to move on to other, more interesting diversions, usually involving Krypto and a mess of some kind.

On this occasion she lost interest around the time Lena was describing her first steps, her hand grasping onto Krypto’s fur to help keep her upright. She finally let go and ventured a couple of paces on her own before falling flat on her butt. Her face contorted like she was about to cry, but Krypto saved the day by licking her in the face until she began to giggle happily.

It was one of Kara’s favorite memories. They were all her favorites, really.

“I wanna play sharks with Krypto!” Libby declared, sitting up and bouncing in Lena’s lap.

“Sharks” was a game Libby _loved_ to play and that Krypto seemed to endure good-naturedly, that involved Kara affixing a shark fin to Krypto’s back and then setting him loose to follow at Libby’s heel while she swam around the house, attacking unsuspecting fish while they were trying to do very boring fish things like make breakfast or clean the living room or read a book.

It kept Libby entertained for quite a while (for a four year old, anyway) and Krypto never failed to stay by her side the entire time. He was always with her, no matter what she was doing. He made it perfectly clear who he preferred.

Kara shook her head as she put Krypto’s shark fin on and Libby took off. She was so full of energy, so smart and weird and so much like Lena.

Kara’s love for Libby and her mother felt heavier inside of her every day, her love for them and what they had created together, whatever it was. It was so fragile, so tenuous, Kara tried so hard to protect it and now she feared it would be washed away in the tide of her feelings.

Because what if Lena didn’t feel the same way? What if Kara ruined all she’d put so much of herself into? What if this fragile, precious thing she held in her hands but that could so easily slip through her fingers, what if this beautiful, amazing, wondrous thing just.

Disappeared.

What if the family of her own she’d finally, finally found, was taken away from her?

Kara didn’t know what she would do.

But it didn’t matter anymore because the Momma story, and all the truths that weren’t quite the real truth, in totality, formed the exact shape of her desire. Everyone could see it, plain as day. Alex, Maggie, her mom, her coworkers, everyone.

Everyone save Lena, maybe.

Which was why Kara had to tell her the truth. It just wasn’t fair to keep it from her anymore. Not when she felt so strongly. She’d given herself 30 days to come clean. Today was day 31.

It was now or never.

Kara sighed as she climbed back into bed, crawling under the covers and pulling Lena into her arms. She just wanted to hold her for a little bit before she laid everything on the table. Lena was so warm, so soft, so utterly, utterly perfect it made Kara ache.

“Hey,” Lena said into a yawn, snuggling into Kara’s side.

“Hey,” Kara said back, breathing in the scent of Lena’s shampoo. It made her lightheaded.

“There’s nothing for her to get into is there?”

“Nah, I think we got everything put up last night. They should be fine for at least twenty minutes.”

“Twenty entire minutes? That’d be a record.”

“I’ll get my stopwatch.”

That made Lena laugh. She was so pretty when she laughed. The more time Kara spent with her the more she seemed to open up, to come into herself. She used to be so subdued, so... controlled. Now she laughed unabashedly, her entire body shaking with it at times, like she was letting go, just a little.

Like she was happy.

They could be happy together, the three of them. Kara knew they could. But only if Lena wanted it. Only if Lena loved her back. It was terrifying to want something so badly.

She kept trying to bargain with herself. She just needed a little more time, a little more so she could prove to Lena what a good mother she could be, what a good wife. But no. She’d had plenty of time. Lena either loved her or she didn’t, and no amount of time was going to change what was already in her heart.

“Can I talk to you about something?” Kara tried valiantly but still failed to hide the tremor in her voice. She didn’t want to scare Lena, but it was so hard to be calm when she was so afraid herself.

“What? Is something wrong?” Lena’s hands curled into Kara’s shirt, her body tensing against Kara’s side.

“No, no. There’s nothing wrong. I just have something I want to ask you.”

“Oh. What is it?”

“This Friday is the holiday party at work, and I was wondering if you and Libby might want to come.”

“But isn’t that just for you and your coworkers?”

“And our families.”

“Families?”

“Yeah,” Kara said brightly. “Do you want to come? I think there’ll be other kids there for Libby to play with. My coworkers are all really nice. I know they would love to meet you.”

“They would?”

“Of course.” Kara cleared her throat one too many times and then tried to cover it with a cough. “I kind of talk about you and Libby a lot.”

“You do?”

“Well, yeah. You’re my two favorite people. So... do you want to come?”

“Ok,” Lena said, ducking her head, the light through the window revealing the amber highlights in her hair.

She was so pretty and so soft. Kara just wanted to touch her, to kiss her, to finally find out how soft her lips really were.

“There’s one thing I need to ask you first though, just so that we’re clear, and on the same page about everything.”

“Um, ok...” Lena’s brow furrowed just slightly, and there was a hint of movement of her bottom lip.

“We’ve been living together for a while, but we’ve never really talked about what we are.”

“What we are? I don’t think I understand.”

“Well, we’re roommates, and we’re friends. But we sleep in the same bed, and Libby calls me Momma.”

“Is that bad? Are we doing something wrong?”

“No, it’s not bad, and we’re not doing anything wrong. I just think we need to talk about it.”

Lena was getting increasingly anxious and fidgety. Kara just needed to get it over with.

“I need to know how to introduce you to my friends. I need to know if...” she stopped for a moment to find Lena’s hand and give it a reassuring squeeze. Lena smiled but still looked very concerned, “if you want me to introduce you as my friend, or, um... as my, you know... girlfriend.”

Kara could feel herself blushing all the way to her ears. But that didn’t matter because she said it. She actually said it. She tripped over herself trying to get the words out, but she did it. Now all she could do was wait for Lena’s response.

“Girlfriend? Are you asking me if I want you to pretend we’re girlfriends?”

Kara winced. “No, Lena. That’s not what I’m asking you. I’m asking you if you want to _be_ my girlfriend.”

Lena still looked confused.

“I have feelings for you. Romantic ones.”

“ _Oh._ ”

Kara’s stomach sank. She was having trouble reading Lena’s expression, and the longer Lena was silent the more Kara became convinced that her answer would not be favorable.

“Are you... in love with me?”

Lena’s words and the look on her face were like a lance through Kara’s heart. She wished she could take it back. She’d been greedy. She’d wanted too much, hoped for too much. And now she feared she would lose everything.

She held Lena’s gaze, a tear slipping from her eye. “I’m sorry, Lena, but, yes, I am. I have been for a long time.”

Lena started to cry, and that hurt Kara even more.

“I, um... I can go, if you want, so you can have some space. I know it must be a shock to you. I’m sorry if I made you uncomfortable. I just had to tell you the truth.” She shifted away from Lena, making to slip from the bed and go cry in the bathroom, but Lena’s hand on her arm stopped her.

“Please don’t go.”

“What?”

“Do you mean it?” Lena asked, staring at her hand where it was fiddling with the fabric of Kara’s shirt. “Do you really love me like that?”

“Yes. Of course I do.”

And then Lena smiled. It was the prettiest thing she’d ever seen. Lena let go of Kara’s shirt and wiped the tears from under her eyes. “I’m in love with you too, Kara. I just never in a million years thought that you’d love me back.”

“That’s funny,” Kara said, so overjoyed she was practically sobbing. “I thought the exact same thing.”

“Do friends really not ever sleep in the same bed?”

“They do sometimes, but probably not every night. And they don’t usually coparent a child together.”

“I guess that makes sense.”

“I mean, I’m not saying it’s never happened, but it’s not common.”

“Kara, can I ask you something?”

“You can ask me anything.”

“Will you kiss me?”

“It would be my pleasure,” Kara said, leaning toward her, her whole body buzzing.

Kara moved in slowly, giving Lena ample time to change her mind. She stopped when their lips were just brushing, a gentle tease she couldn’t resist. “Are you sure this is what you want?”

Lena framed Kara’s face with her hands, pulling her into a kiss that started out slow, careful, almost timid. Lena was so soft, tasted so sweet, and the floral scent of her shampoo made Kara swoon. Warmth tingled in her chest, like she was so filled to the brim with happiness, with _Lena_ , that it all spilled over and she was utterly awash in it.

When they finally broke apart, Lena was wearing an impish smirk and Kara could tell that her ears were blushing again. All she could think about was that kiss and how much she wanted to keep kissing Lena until they couldn’t stand to kiss anymore, if that was even possible.

“I, um,” Kara started, “can we do that again?” She leaned forward, ready to feel Lena’s mouth on hers once more.

“Yes, I think we def—”

“WATCH OUT! HERE COMES A SHARK!” Libby shrieked happily before leaping onto the bed with them. Krypto, thankfully, did not try to follow her and waited politely on the floor, his fin slightly askew.

Kara, needing only half a beat to get her bearings, wailed in mock horror, flopping back onto the bed. “Noooooo! Please don’t eat me! I am just an innocent fish!”

“I’m gonna eat you Momma!” Libby yelled, and proceeded to do just that, not even leaving Kara one fin with which to protect herself.

“Oh, no! You got me!” Kara closed her eyes, letting her tongue loll out of one side of her mouth.

“I ate you, Momma!” Libby said, matter of factly, as she crawled on top of Kara. She patted the side of her face. “Momma wake up.”

Kara opened one eye to peer at Libby. “What?”

“I ate you!”

“You did. I’m so proud of you! Are you going to eat Mommy too?”

Libby looked over at Lena, humming thoughtfully. “I’m full now.” She patted her belly. “I’ll eat Mommy later.” She leapt from the bed and darted out of the room, Krypto at her heels.

“That was brutal,” Lena said, snuggling up to Kara’s poor, mangled fish body. “You lost all your fins again.”

“Yes. It was _terrible_. I think I need you to kiss me to make it better.”

“That can be arranged.” Lena picked up her hand and kissed each of her fingertips before moving to her palm, the inside of her wrist, and finally, the back of her hand. She repeated the process with Kara’s other hand. “All better?”

“Almost.”

“Where else does it hurt?”

“Right here,” Kara said, pointing to her mouth.

Lena kissed her tenderly, lingering for a moment, and then laid her head on Kara’s chest, yawning. “So how long was that? Anywhere near twenty minutes?”

Kara grabbed her phone off the nightstand to check the time. “Not even close.”

Lena laughed. “We should definitely get some cuddling in before she comes back for me.”

“I think that’s a fantastic idea.” Kara bent her head to press a kiss into Lena’s hair. “But you’ll have to do the holding this time.” She said, gesturing at herself. “You know, no fins.”

“I think I can do that.” Lena said, wrapping her arms around Kara. “Is that good?”

“Perfect.” Kara sighed contentedly, but then a thought struck her. “I do have another question, just to be clear. Do you want me to introduce you to my coworkers as my girlfriend, or no?”

Lena laughed and pulled Kara into a kiss. “Of course I do, you silly fish.”

**Author's Note:**

> I hope you liked this Mommates AU AU ficlet that got away from me. 
> 
> Also s/o to the very sweet, sad anon who inspired me to write it! 💜💜💜
> 
> As always, you can come talk to me on [tumblr](https://drfitzmonster.tumblr.com/) or [twitter](https://twitter.com/drfitzmonster): @drfitzmonster


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